(() => {
  console.log(Math.floor(3.14));// 输出: 3 
  console.log(Math.floor(5.7));// 输出: 5 
  console.log(Math.floor(-2.5));// 输出: -2 
  console.log(Math.floor(10));// 输出: 10
  console.log(~~3.14);
  console.log(~~5.7);
  console.log(~~(-2.5));
  console.log(~~10);
})()